A. Field of the Invention
The present invention relates generally to bodyboards and stiffening elements thereof.
B. Discussion of Related Art
Sports boards composed of a preformed, preshaped, generally planar foam core with a slick bottom skin are very popular for use on water, snow, grass, ice or other surfaces. One type of sports board comprises a bodyboard or surf board and is employed in the water, more particularly for wave surfing. Generally, bodyboards are made of semi-rigid foam core, typically with polystyrene foam, polyethylene foam or polypropylene foam, and have polyethylene foam sheets laminated to the top and side surfaces of the foam core, and have a bottom surface composed of a polymeric film material, to provide a low-frictional slick surface for gliding purpose.
During wave riding, a user may bend the board and turn on the water. The board typically restores to neutral position after bending. The recovery of original shape is always referred as the ‘memory’ of the foam core. Polypropylene foam core has better memory characteristics than other foam core materials. Therefore, polypropylene foam core is typically used for high end performance bodyboards due to its resilient, rigid and light weight physical properties.
Typically, bodyboards are ridden in a prone position, with one arm extending forwardly for gripping the nose and the other arm positioned in a trailing manner for gripping the front portion of the side edge of the bodyboard. With the arms and hands thus positioned, the rider can push or pull against the engaged front or side edges to bend or twist the board to increase friction and drag on selected parts of the board, which help the rider in redirecting the board. The force applied to the bodyboard that only distorts the board does not help the rider. Thus, a high degree of stiffness of the bodyboard is desirable. However, it may not be desirable to make the bodyboard very rigid entirely from the nose to the tail. For example, it may be desirable for the board to be more flexible at the portion between a transverse line about a quarter of the way from the nose and the lead nose. Such flexibility allows the rider to pull up the nose of board and steer the board to the desirable direction in wave surfing. It is therefore desirable to provide an improved bodyboard with stiffening element(s) adapted to provide the resistance to flex on the major supporting region of the board and yet allow adequate flexibility along a longitudinal axis of the foam core in the forward quarter of the board.
A variety of stringers and stiffening methods have been described in the prior art. U.S. Pat. No. 6,036,560 issued to Pekar on Mar. 14, 2000, filed Feb. 5, 1999, the disclosure of which is incorporated herein by reference, shows a flexible stringer rod that imparts flexibility to the front nose area of a bodyboard. The flexible front nose area provides greater maneuverability for the bodyboard. The Pekar patent shows an elongated stringer element comprising a stiff portion of fiberglass or graphite resin-impregnated material and a flexible portion of a front tip end of a polyethylene material, and generally longitudinally arranged within the foam core material and extending substantially from the tail end toward the front end.
The disadvantage of using a solid plastic rod such as polyethylene in the front portion of stringer is that the recoil of the polyethylene rod is very slow and the stringer does not return to the original straight shape spontaneously. Changing the stiffness of the bodyboard is also accomplished by external means. As an example for comparison, U.S. Pat. No. 5,224,890 invented by Moran issued on Jul. 6, 1993, the disclosure of which is incorporated herein by reference, shows a fiber mesh stiffener for selected regions of differing stiffness in order to combine in one board the speed associated with relatively stiff bodyboards and the maneuverability of soft bodyboards. Laminated into the layered structure of the bodyboard is a fiber mesh. The fiber mesh is an example of an external stiffening method. It is obviously more desirable to obtain an improved bodyboard with a variable flexible stringer that responses instantaneously with the bending force applied by rider.
One conventional method of strengthening bodyboard is to insert one or more cylindrical rods, know as stringers, into holes drilled parallel to the longitudinal axis of the board from the tail end toward the nose end. A stringer system would generally include a fiberglass or graphite rod that is centrally inserted and adhesively secured in the foam core material. The disadvantage of the current stringer systems used is that the stringer may separate from the foam core after frequent use, in extreme conditions of use, for example when the board is bent up harshly, the stringer rod can pop out of either the deck or the bottom of the bodyboard. It would be desirable to provide an improved stringer element composed of two sections, rear section composed of a material to impart stiffness to the bodyboard, while the front or tip section of the stringer element composed of a flexible material to permit flexing of the nose and front portion of the bodyboard by a rider.
Thus, it is one object of the invention to provide a polyolefin foam sports board with improved handling and customizable stiffness.